8o Veterinary Medicine. 



pneumonia, and further that of erysipelas of man, as a wise health 

 officer would differentiate the microbes of cowpox and smallpox. 

 Whatever may be true or false as to their primary identity, or as 

 to the transition of one to the other in successive inoculations on 

 animals of other genera, they are essentially diverse pathogenic- 

 ally as we meet with them in practice, and our measures may be 

 safely based on this practical diversity. 



Accessory Causes. Youth strongly predisposes, most cases 

 occurring between two and five years, and seventy per cent, before 

 five years. It may, however, appear at any age, being congenital 

 in .some cases (Nocard, etc.), in others appearing a few weeks after 

 birth, and in .still others at over twenty years, if the subjects have 

 not contracted it earlier. 



Dentition which is active in these early years, induces conges- 

 tion about the head and general constitutional disturbance, which 

 make the system more receptive. 



Training or breaking is another reason for the predisposition 

 in the young. The first experience of the hot, impure, infected 

 air of the stable, the unwonted grain feeding , the excitements and 

 perspirations attendant" on the first handling all contribute to 

 temporary loss of resistance. 



Fatigue like other weakening conditions lays the .system open 

 to attack. 



Oz7/isamost efficient cau.se, hence the disease often prevails 

 most extensively in spring and autumn, at the time of changing 

 the coat, and of passing from stable to field and the converse. 

 Joly relates that in Russia where large numbers die of strangles 

 through imperfect .stabling in winter, immunity is sought through 

 a milder first attack, brought on in the milder autumn weather by 

 turning the young animals into a deep pool for half an hour and 

 then exposing them freely to cold winds and giving cold water to 

 drink. The omnipre,sent germ takes occasion to attack the cold 

 debilitated system. 



Any change of latitude or of locality acts in the same way. 

 Riquet even alleges that this will bring about a second and even 

 a third attack. It is common, he .says, for newly bought young 

 horses to have the disea,se at Hamburg, and after recovery to have 

 a second attack at Hanover and finally a third one after they join 

 the regiments in France. A similar exhaustion of immunity has 

 been repeatedly noticed in the case of canine distemper. 



